The primary purpose of the proposed research is to determine the effects, as well as limitations, of cognitive factors in human autonomic conditioning. More specifically, we are developing and testing methods of measuring awareness of the CS-UCS relation during (rather than after) a pavlovian conditioning session. In this way, we hope to determine the temporal relationship between the development of conditioning and awareness. We are also employing masking tasks so as to determine the effects of preventing awareness on human conditioning.